It is generally known to provide a sliding door for van-type vehicles, where the door is moved along a fixed path generally parallel to the side wall of the van for a major portion of its opening and closing movement. Typically, the sliding door of a van-type vehicle moves generally into the plane of the door opening during a portion of its respective final closing and initial opening movements, so as to be flush with the side wall when fully closed, and moves generally out of the plane of the door opening during its initial opening movement so as to be along side of, and parallel to, the side wall of the vehicle in a position generally to the rear of the door opening when fully opened.
In van-type vehicles having sliding door systems, typically upper and lower forward guide rails or tracks are attached to the top and bottom portions, respectively, of the portal defining an opening through the wall of the vehicle, and a rear guide rail is attached to the exterior of the side wall, at an elevation approximately midway between the elevation of the upper and lower forward guide rails. The respective forward end portions of the various guide rails are curved inwardly with respect to the vehicle body, and bracket and roller assemblies are fastened to the respective upper and lower forward ends of the sliding door, as well as to an intermediate position at the rear end of the sliding door. The bracket and roller assemblies are slidingly supported in the guide rails to guide the door through its opening and closing movements.
Movement of the sliding door through a major portion of the rearward track or guide rail extending generally parallel to the side wall of the vehicle requires high displacement with low force to achieve the transitional movement, since only frictional resistance and gravity resistances due to changes in grade must be overcome. The movement of the sliding door through a forward portion of the guide rail track, curved inboard with respect to the vehicle, requires a low displacement with high force. The forces associated with an elastomeric weather seal surrounding the door opening must be overcome and an unlatched striker or fork bolt on the door must be engaged by a corresponding fork bolt or striker at the rear portion of the van body door opening. During manual operation, sliding van doors are typically moved with great momentum through the entire closing movement in order to ensure full weather strip compression and latch operation at the end of such movement.
A typical standard automotive door latch assembly includes a striker, which can take the form of a pin or a U-shaped member, fixedly mounted in the door frame to project into the door opening and into the path of movement of a latch member mounted on the edge of the door, which includes the fork bolt therein. The latch member is typically movably mounted with respect to the door and arranged so that as the door approaches its closed position, the latch member will engage the striker and further closing movement of the door will move the latch member into safety latch position with respect to the pin, sometimes referred to as the secondary latch position, and further closing movement of the door will move the latch member into a primary latch position with respect to the pin, which positively retains the door against movement away from its closed position. It is generally known for at least part of the movement of the latch member into latched relationship with the striker to be resisted by a spring, and many users of sliding doors of this type habitually close the door with far greater force than necessary to overcome the spring bias. Greater force is generally required in the case of sliding doors, such as those employed in vans, where movement of the door through the final phase of movement to the fully closed position must compress a resilient door seal which extends around the entire periphery of the door opening.
Power striker devices have been proposed to overcome the high force requirements to move sliding doors into the fully closed position. Typically, the power striker devices are mounted on the door frame for powered movement between an outboard ready position with respect to the vehicle centerline where the latch is engaged with the striker and an inboard holding position where the striker holds the latch door in the fully closed position. It is still required in such systems to use high force or momentum in order to ensure that the latch engages the striker in the primary latch position prior to movement into the fully closed position. When the door is open, the striker is located in its outboard ready position. After closing translation of the door is complete, the latch on the door engages the striker and latches the door to the striker while the striker is still in the outboard position. The door may engage a limit switch on the door frame when in the outboard position to actuate a drive motor which, through appropriate mechanism, drives the striker to its inboard position, such that the latched engagement between the door and striker enables the pin to drive the door to the fully closed position. With this arrangement, a closing force sufficient to engage the latch to the primary latch position with respect to the striker needs to be applied. The powered movement of the striker provides the force necessary to compress the door seal. If the striker and latch do not reach the primary latch position with respect to one another, the powered movement of the striker from its outboard position to its inboard position would not be sufficient to bring the door to the fully closed position in sealed engagement with the frame around the periphery of the door opening. In such cases, the user may be required to reopen and close the door repeatedly until the latch and striker are disposed in the primary latch position with respect to each other when in the outboard position.